aka man of the earth; Ipomoea pandurata; Convolvulaceae (morning glory family)
Neither a potato nor a man (though it is of the earth; see how useless common names are?), this plant is related to sweet potato (Ipomoea batatas). It can be distinguished from other similar species in this area (3 native and six alien) by the purple throat. This vining plant that can grow to 15 feel in length. Roots can weigh up to 20 pounds and are supposedly edible, if they can be extracted from the earth.
Found throughout the eastern US and the prairie midwest, it is listed as threatened in Michigan and endangered in New York, but as a noxious weed in Arkansas and a prohibited noxious weed in Arizona. It is closely related to both the pretty morning glories you planted around your mailbox and the annoying bindweed that grows through all your other garden plants.